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Recently, I have raised the lower limit of my pressure range from 6.0 to 7.0 cm on my S9 Autoset. I did this because the median pressure Rescan reported for the last month was 7.9. I figured that tightening up the treatment pressure range (7.0 -16.0) might help my AHI numbers a bit. What I found happening, instead, was that the AHI went up drastically. When I looked closely at the data, it appearded that I was having central apneas while trying to fall asleep. I was also having central apnea events when I layed in bed in the morning after awakening. In between, I was having only an occasional obstructive or hyponeic event. While I am not worried about this (my overall AHI for the night was only 3.2 even with the central apneas), when I look at the AHI for the first 40 minutes while I am watching TV and trying to fall asleep, I had as many as 6 central apneic events. What's going on here?

I am not sure, but here's one guess. With the new higher initial pressure, I may be hyperventillating a bit, as I try to overcome and get used to the new higher initial pressure. Then, I may be pausing and not breathing long enough (4 sec) for the S9's CSA detector to send out a test pulse to see if the airway is clear or not. It's clear, so the S9 doesn't increase the pressure, but then goes on to record a central event. (The events aren't long, so I think this may be the case.)

Though it's really not a problem, I just wonder how to overcome these awake apneic events. I tried setting the EPR up to 3 (usually it is off), but that made no difference. I could try ramping the pressure up over the first hour from my old setting to the 7.0 and see if that makes a difference. I haven't, yet. Or I could just not worry about it, although I am OCD enough to bring this "problem" up here, to see if others have ever noticed this happening to them.

The theory is that the higher pressure raises the blood oxygen level. The brain then signals the lungs to stop breathing. Because there's an adequate supply of oxygen in the blood, the brain figures breathing is not necessary.

Quote: I did this because the median pressure Rescan reported for the last month was 7.9. I figured that tightening up the treatment pressure range (7.0 -16.0) might help my AHI numbers a bit.

7.9 is much closer to the bottom end of your range than to the upper end. If my theory is correct, it seems you would've been spending a significant amount of time with your pressure between 6.0 and 7.0.

Look and see if you're spending much time near the upper end of the range. Once you reset the lower end to 6.0, and get your AHI back where it was, you might want to set your upper end of 16.0 to something smaller. That would acheive your original goal of tightening up the treatment pressure range.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.

(06-15-2012, 12:01 PM)Sleepster Wrote: Raising the pressure is what induced the CA's. Set it back to 6.0.

The theory is that the higher pressure raises the blood oxygen level. The brain then signals the lungs to stop breathing. Because there's an adequate supply of oxygen in the blood, the brain figures breathing is not necessary.

Quote: I did this because the median pressure Rescan reported for the last month was 7.9. I figured that tightening up the treatment pressure range (7.0 -16.0) might help my AHI numbers a bit.

7.9 is much closer to the bottom end of your range than to the upper end. If my theory is correct, it seems you would've been spending a significant amount of time with your pressure between 6.0 and 7.0.

Look and see if you're spending much time near the upper end of the range. Once you reset the lower end to 6.0, and get your AHI back where it was, you might want to set your upper end of 16.0 to something smaller. That would acheive your original goal of tightening up the treatment pressure range.

My max pressure reading for the night was 15.9. That's why I didn't adjust that downward. 95% of the time the pressure was less than 8.0.
I therefore thought that 6.0 ccould be easily raised to 7.0. I could understand having more central events if I raised the upper number too much. I just don't understand how going from 6.0 to 7.0 on the low end is having the effect that it is, WHEN I AM AWAKE. After I fall asleep, there is no problem with supposed central events. (Are they events at all, or just the pecululiarity with which the S9 tries to check out irregularities in the breathing and the way it reports it?)

Raising pressures is not like changing your air con in your home or car, the slightest raise can cause many problems. Class this as a warning and bring your pressure back down. If your using an apap then it will raise on its own accord and doesnt need tightning. My raise went from 4 to 10 which took me 5 months to do, my pressure readings are around 11-12cm but I wont tighten anymore as my machine will pick up any raise and its good to give your machine some room to operate. If anything seek medical advise before changing anything or at least please make sure you know what your doing and the risks.

Apnea while you,re asleep not while you,re awake. The S9 can not distinguish if you,re awake or asleep it flag events as it see them and all apnea events while awake are discarded and subtracted for a true AHI. Pay a little attention to your sleep hygiene and avoid caffinated or alcoholic drinks late at night. If your nose feel slightly congested try sinus rinses.

(06-15-2012, 01:27 PM)zonk Wrote: Apnea while you,re asleep not while you,re awake. The S9 can not distinguish if you,re awake or asleep it flag events as it see them and all apnea events while awake are discarded and subtracted for a true AHI.

If it can't distinguish between if you're awake or asleep, how does it know to discard the events while awake?

(06-15-2012, 01:27 PM)zonk Wrote: Apnea while you,re asleep not while you,re awake. The S9 can not distinguish if you,re awake or asleep it flag events as it see them and all apnea events while awake are discarded and subtracted for a true AHI.

If it can't distinguish between if you're awake or asleep, how does it know to discard the events while awake?

There is no way the S9 know can know if you are asleep or not. But you have to know when you are and then disgard those "central events" that occur you are awake. They are really meaningless, unless perhaps you have a neurological problem, in which case, you will also see those happen when you are asleep.

(06-15-2012, 12:21 PM)BabyDoc Wrote: 95% of the time the pressure was less than 8.0.

That means you were spending 95% of your time with your pressure beween 6.0 and 8.0.

Quote:My max pressure reading for the night was 15.9.

What was the min pressure reading?

Based on the numbers you're giving us, I would conclude you were spending a significant amount of time with your pressure below 7.0. When you adjusted your pressure range you prevented the machine from doing that anymore and your CA index went up.

You say these CA events are ocurring when you're awake. Maybe you were, maybe you drifted off and weren't aware of it. Regardless, what difference does it make?

Why would you want to deprive yourself of the therapy you were getting with pressures between 6.0 and 7.0?!

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.

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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.